February 28, 2011

Morning Sickness – should it be called that?

Nausea and vomiting in pregnancy is a common condition, affecting up to 80% of pregnant women, but yet it remains vastly under-researched and under-appreciated.

‘Morning sickness’ as a description has been around for many years, but it misrepresents and trivialises the condition. There are many possible causes of the condition, but precisely why it occurs is still largely unknown.

Dr Roger Gadsby, MBE, GP and Associate Clinical Professor at Warwick Medical School, has been researching the condition for nearly 30 years, and in 2002 helped to set up a small charity called Pregnancy Sickness Support to give information and support to women suffering from the condition.

Roger's comments:

"In 1993, I worked with others to publish a ground breaking paper of the condition in 363 women from my practice. This paper has, at the last count, been cited over 186 times and is still the only prospective, descriptive, community-based account of the condition to date. It found that nausea occurs just as commonly after midday than before, and whilst vomiting occurs more usually in the mornings it can happen at any time during waking hours. The more accurate description of the condition would be ‘episodic daytime pregnancy nausea and vomiting’ but that doesn’t have the same catchy quality as ‘morning sickness’, does it?

"One of the reasons I began my research was when a patient came to me saying: 'I have had such severe nausea and vomiting symptoms that I don’t want to have any more children, what causes it?' It can be so severe that women suffering from it have to terminate their pregnancy, such is the impact of the condition.

"In my research, pregnancy nausea and vomiting was positively related to weight of the placenta and I believe the condition is also related to the intense immunological suppression that takes place which enables an immunologically foreign foetus to develop without being rejected by its mother. The research has also shown an association between the symptoms and blood levels of prostaglandin E2 a cytokine involved in this immunological suppression.

"I am committed to continuing my research, which I hope will help inform and improve the treatment of morning sickness for thousands of women."

To hear Dr. Gadsby talking about morning sickness and the possible causes, tune into Radio 4’s Case Notes programme with Dr Mark Porter. It is due for broadcast on 1 March at 9pm and will be repeated on Wednesday 2 March at 4.30pm

One comment

Robert Carter

Dear Dr Gadsby, I listened with interest to the recent case notes programme. I worked in various pharmaceuticals companies in drug development. I worked on naloxone, namefene and naltrexone (opioid antagonists). I worked with a Dr Rust in Frankfurt who did some research on pain thresholds in pregnant women. Using a heat probe on the finger he measured what temperature women could stand before it was unacceptable. The pain threshold increased gradually throughout the pregnancy and, following parturition, returned to baseline (pre-pregnancy) within 24 hours. (I regret that I never followed up to find out whether this work was published, although the observations were made in about 1985. I am no longer involved in drug development and am unable to do appropriate searches). Our thoughts at the time were that endogenous opioids were responsible for the gradual increase in pain threshold. This would make sense in that giving birth is a painful business. Opioids may also be involved in grooming behaviour and, I think they enhance smell(?). Most importantly, opioids cause nausea & vomiting. The fact that most morning sickness disappears around the end of the first trimester might be explained by tolerance. I am certainly not proposing a trial on trial on an opioid antagonist but I would be most interested to know whether there has been any work on a correlation between endogenous opioids and morning sickness.

Kind regards, Rob Carter.

04 Mar 2011, 15:01

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